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AGGRESSIVE CHEMICAL DECONTAMINATION TESTS ON VALVES FROM THE GARIGLIANO BWR

Objective

THE AGGRESSIVE CHEMICAL DECONTAMINATION METHODS, WHOSE EFFECTIVENESS HAS BEEN PROVED BOTH IN MANY LABORATORY TESTS AND IN PRE-INDUSTRIAL APPLICATIONS, APPEAR TO NEED FURTHER INVESTIGATIONS REGARDING BOTH THE DECONTAMINATION OF COMPLEX SYSTEMS, SUCH AS VALVES, AND SPENT DECONTAMINANT TREATMENT IN VIEW OF THE LIMITATION OF THE SECONDARY WASTES ARISINGS.
THE SCOPE OF THE RESEARCH IS BOTH TO CHECK THE EFFECTIVENESS OF HARD CHEMICAL DECONTAMINATION ON USED COMPONENTS, SUCH AS SMALL VALVES, AND TO SEARCH AND DEVELOP A SUITABLE AND SAFE PROCEDURE TO TREAT SPENT SOLUTIONS, ARISING FROM AGGRESSIVE CHEMICAL DECONTAMINATION.
THE ADVANTAGES OF THIS RESEARCH ARE THE POSSIBLE DEMONSTRATION OF THE DECONTAMINATION EFFECTIVENESS ON COMPLEX COMPONENTS AND THE MINIMIZATION OF THE TOTAL WASTES PRODUCED.
THIS PROPOSED RESEARCH WILL BE CARRIED OUT IN COLLABORATION WITH CISE IN THE FRAMEWORK OF A SPECIFIC MULTI-ANNUAL AGREEMENT ALREADY IN FORCE. THE EXPERIMENTS WILL BE PERFORMED IN DECO LABORATORY AT ISPRA, JRC.
REGARDING THE APPLICATION OF CHITOSAN, SPECIFIC AGREEMENTS WITH THE UNIVERSITY OF ANCONA HAVE ALREADY BEEN UNDERTAKEN.
In order to check the effectiveness of direct chemical decontamination on small and complex components, usually considered for storage without decontamination because of their small number, some tests were performed on the DECO experimental loop. 4 small stainless steel valves from the primary system of the Graigliano boiling water reactor (BWR) were decontaminated using mainly aggressive chemicals such as hydrochloric acid, hafnium, nitric acid and their mixtures. On 2 valves, before the treatment with aggressive chemicals, a step with soft chemicals (oxalic and citric acid mixture) was performed in order to see whether a softening action enhances the following aggressive decontamination.
1. AGGRESSIVE CHEMICAL DECONTAMINATION TESTS ON VALVES (2-3 INCHES) OF THE PRIMARY COOLING SYSTEM OF THE GARIGLIANO BWR IN DECO LOOP.
2. IDENTIFICATION AND QUALIFICATION OF A SIMPLE PROCEDURE TO CONDITION THE SPENT DECONTAMINANT.
3. NEUTRALIZATION AND FLOCCULATION TESTS IN ORDER TO SELECT AND EVALUATE THE BEST NEUTRALIZING AGENT AND SPECIFIC CHEMICAL AGENTS, SUCH AS CHITOSAN, AS SUPPORTER IN FLOCCULATION.
4. DEVELOPMENT OF THE DECONTAMINATION PROCESS BY USING ULTRASOUNDS TOGETHER WITH AGGRESSIVE CHEMICALS.
5. DECONTAMINATION TESTS WITH THIS METHOD ON CONTAMINATED SAMPLES OF ABOUT 10 CM2 SURFACE (STAINLESS AND CARBON STEEL). IF THE RESULTS OF THE PREVIOUS TESTS ARE SATISFACTORY, THE DECONTAMINATION PROCESS WILL BE APPLIED TO A LITTLE VALVE (1-2 INCH)
6. RADIOCHEMICAL MEASUREMENTS ON SELECTED SAMPLES BEFORE AND AFTER DECONTAMINATION, IN PARTICULAR FOR THE FOLLOWING ELEMENTS: FE-55, NI-59 AND NI-63.
7. COST EVALUATION OF THE PROCESS AND ASSESSMENT OF THE POSSIBILITY OF REPROCESSING AND REUTILIZING OF SPECIFIC AGENTS.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

Ente Nazionale per l'Energia Elettrica SpA (ENEL)
Address
Via Monfalcone 15
20132 Milano
Italy